Balanced pressure gage and switch



March 9, 1948. D. L. RIGDEN 2,437,440

I BALANCED PRESSURE GAGE AND SWITCH Filed Jan. 4, 1945 INVENTOR. Dayan/vA. P/ame/v HTZ'OENE Y5 Patented Mar. 9, 1948 UNITED STATES PATENT OFFICEBALANCED PRESSURE GAGE AND SWITCH Duncan L. Rigden, Oakland, Calif.

Application January 4, 1945, Serial No. 571,245

(Cl. 200-8L6) Claims. 1

The present invention relates to improvements in a balanced pressuregage, and it consists of the combinations, constructions andarrangements hereinafter described and claimed.

An object of my invention is to provide a balanced pressure gage whichis intended to register the pressures of liquids or gases visually andis especially designed to operate at extremely low pressures as well asany other pressure desired.

A further object of my invention is to provide a device of the tybedescribed in which the usual spring actuated plunger is dispensed withand instead I make use of two pistons and place them in equilibrium. Oneof the pistons is actuated by the liquid or gas pressure in the line andthe other piston actuates the liquid for moving it in a calibrated tube50 that the pressure can be visually read.

A further object of my invention is to provide a device of the typedescribed which is extremely simple in construction and which is durableand efficient for the purpose intended.

Other objects and advantages will appear in the following specificationand the novel features of the device will be particularly pointed out inthe appended claims.

My invention is illustrated in the accompanying drawing forming a partof this application, in which the figure shows a vertical sectionthrough the device, portions thereof being shown in elevation.

While I have shown only the preferred form of my invention, it should beunderstood that various changes or modifications may be made within thescope of the appended claims without departing from the spirit and scopeof the invention.

In carrying out my invention I provide a casing A that has a cylindricalortion A tapped at l for receiving the threaded end 2 of a T indicatedat 3. The T is connected in a pipe B through which a liquid or a gasfiows under pressure.

A cylindrical body C is secured to a flange 4 of the casing A. Anysecuring means may be used and I have shown bolts 5 that are passedthrough openings 6 of the flange 4 and openings 1 in a flange 8 of thebody C. A cover D is secured to the flanged end 9 of the body C by boltsID that are passed through aligned openings II and I2 formed in theflange 9 and cover D respectively. The cover D has an exteriorlythreaded outlet l3 and a calibrated transparent tube [4 is held incommunication with the outlet by means of a coupling 15. A gasket 16 isplaced between the flanged end or the tube I4 and the end of the outletl3.

Fundamentally the gage consists of two cylinders A and C and thecylinder A carries One or more pistons E that are connected in tandem bya threaded shank I1 that extends downwardly from a head l8. A secondpiston F of a larger area than the piston E is mounted in the cylinderbody C and has a head l9 projecting downwardly from the rubber apron 20that forms a part of the piston. A flexible diaphragm G is clampedbetween the body C and the casing A so as to make a hermetically tighthi; and the diaphragm extends between the heads l8 and i9.

Gaskets 2| and 22 are placed between the flanges 4 and B and the flange3 and the cover D respectively, for forming hermetically tight joints. Ableed opening 23 communicates with the compartment H formed by thediaphragm G and the casing A. A second opening 24 communicates with acompartment K formed in the body C and bounded by the diaphragm G andthe piston F. If desired, the openings 23 and 24 may be tapped forreceiving pipes, not shown. The tube It is calibrated at 25 forregistering different liquid levels.

From the foregoing description of the various parts or the device, theoperation thereof may be readily understood.

The piston E is connected to the source of liquid or gas supply by the Tshown at 3. Any variation in pressure of the liquid or gas in the pipe Bwill actuate the piston E to raise or lower it. The piston E in thedrawing, is shown in its lowermost position. Movement of the piston Ewill flex the diaphragm G and will move the piston F by direct contactwith the head 19. The piston F in the secondary cylinder C will move anddisp ace the liquid covering the piston and force this liquid up intothe calibrated tube I4. I preferably use mercury in the tube It. Thedisplaced liquid rises in the tube l4 until the height of the column ofliquid balances the pressure applied from the source to the piston E inthe primary cylinder A The height of this column of liquid, when viewedthrou h the glass tube, registers visua'ly the pressure from the source.

The drawing illustrates a primary cylinder A having a pistonthree-fourths of an inch in diameter and having an area of .441 squareinch. If two hundred pounds per square inch be applied over an area of.441 square inch the total pressure from the source will be found toequal 88.2 total pounds acting on the primary piston E. The piston E isso designed that it will move the three inch diameter piston F containedin the secondary cylinder C. The liquid displaced by the secondarypiston will rise in the tube M. The area of the secondary piston is 7.06square inches and if mercury is used for the fluid it will be found thatmercury, having a weight of .49 pound per inch of height when applied toan area of 7.06 square inches times .49 will equal an effort of 3.459pounds applied to the top of the secondary piston. Therefore the totaleffort from the source being 88.2 pounds and the weight of a column ofmercury being applied over an area 7.06 square inches equaling 3.459pounds per inch of elevation, it will be apparent that when the mercuryrises to an elevation of 25.5 inches, the secondary and primary pistonswill be in equilibrium and the height of the mercury column willindicate a pressure of 200 pounds per square inch at the source.

For various pressures and sizes, diiierent sized cylinders and pistonsvariously related to each other. may be used. The change in thecapacities of the compartments H and K can take place because air canenter or leave these compartments throu h the openings 23 and 24. Shou dany leakage develop past the pistons E, the liquid or gas enterin thecompartment H would exhaust throu h the opening 23. Also if any leakagedeveloped past the piston F into the compartment K the liquid couldbleed off through the opening 24.

The registering liquid may be mercury, brine. water or any liquid wh chwill give the desired effect in the most practical manner. Should aliquid such as mercury or brine be used, the electrical conduct veualities of that liquid may be made to operate the electrical apparatusat remote points or to indicate pressures at considerable distances fromthe source. I have shown a wire 26 connected to the cover D andhave'shown a second wire 21 connected to a terminal 28 that penetratesthe tube It so as to be contacted by the mercury or brine contained inthe tube when the liquid rises to a height equal to the position of thecontact. Since the tube I4 is glass, the circuit will not be closedbetween the wires 26 and 21 until the electrical conducting liquidreaches the terminal 28. The closing of the circuit can be made to doany work desired.

An important feature of the gage is the corrugated diaphragm Gseparating the primary and secondary pistons E and F. The corrugateddiaphragm is intended to prevent the intermingling of the two fluids, orthe gas and fluid. The diaphragm is corrugated to minimize any frictionwhich might occur due to the stretching of an elastic diaphragm.

I claim:

1. A balanced visual pressure gage comprising a cylinder adapted forcommunication with a line that carries a fluid medium under pressure, apiston mounted in the cylinder and being moved in accordance with thevarying pressures of the medium in the line, a second cylindercommunieating with the first cylinder, a second piston slidably mountedin the second cylinder, a flexible diaphragm separating the twocylinders and being contacted by both pistons, a transparent calibratedtube communicating with the second cylinder, and visual pressureindicating means mounted in the tube and second cylinder and actuated bythe movement of the second piston for indicating the rise and fall ofpressure in the line at all times, said means comprising mercury 4constituting a resisting force to counterbalance the pressure of thefluid medium.

2. A balanced visual pressure gage comprising a cylinder adapted forcommunication with a line that carries a fluid medium under pressure, apiston mounted in the cylinder and being moved in accordance with thevarying pressures of the medium in the line, a second cylindercommunicating with the first cylinder, 2. second piston slidably mountedin the second cylinder, a flexible diaphragm separating the twocylinders and being contacted by both pistons, a vertically disposedtransparent and calibrated tube communicating with the second cylinder,and a liquid medium in the tube and being acted upon by the secondpiston, the level of the medium in the tube indicating the pressure ofthe medium in the line.

3. A balanced visual pressure gage comprising a cylinder adapted forcommunication with a line that carries a fiuid medium under pressure, apiston mounted in the cylinder and being moved in accordance with thevarying pressures of the medium in the line, a second cylindercommunieating with the first cylinder, a second piston slidably mountedin the second cylinder, a flexible diaphragm separating the twocylinders and being contacted by both pistons, a vertically disposedtransparent and calibrated tube communicating with the second cylinder,and a liquid medium in the tube and being acted upon by the secondpiston, the level of the medium in the tube indicating the pressure ofthe medium in the line, said first-named piston, first-mentionedcylinder and diaphragm forming a compartment which is vented to permitthe diaphragm to flex and to permit any leakage of the first-mentionedmedium past the first piston to escape through the vent, saidsecond-named piston, secondnamed cylinder and diaphragm forming a secondcompartment which is vented to permit the diaphragm to flex and topermit any leakage of the second-named medium past the second piston toescape through the vent.

4. A balanced visual pressure gage comprising a cylinder communicatingwith a line that carries a fluid medium under pressure, a piston mountedin the cylinder and being moved in ac cordance with the rise and fall ofpressures of the medium in the line, a second cylinder communicatingwith the first cylinder, a second piston slidably mounted in the secondcylinder, a flexible diaphragm sealing one cylinder from the other andbeing contacted by both pistons, a vertically disposed transparent andcalibrated tube communicating with the second cylinder, and a fluidmedium in the tube and being acted upon by the second piston, the levelof the medium in the tube indicating the pressure of the medium in theline, said second-mentioned fluid medium being a conductor ofelectricity, said calibrated tube being made of an insulating material,a wire in electrical connection with the second-named medium andconstituting a part of an electrical circuit, and at least one electricterminal on the tube and constituting one electrode of a switch, thesecond-named medium constituting the other switch electrode and closingthe circuit when it contacts the terminal.

5. A balanced visual pressure gage comprising a cylinder adapted forcommunication with a line that carries a fluid medium under pressure, aplurality of pistons in tandem mounted in the cylinder and being movedin accordance with the varying pressures of the medium in the line, a

8 7 sccondcylluderotelcrcerdiemeterthsnthe first communicating with thefirst cylinder. s second piston slidsbhr mounted in the second cylinder.n flexible dlnphregm separating the two cylinders and being contacted byboth pistons, a vertically disposed transparent and calibrated tubecommunicating with the second cylinder, and a liquid medium in the tubeand being acted upon by the second piston, the weight oi the secondmedium and the two pistons counterbalancing the pressure or the firstmedium, the level of the second medium in the tube indicating thepressure of the first medium in the line.

' DUNCAN L. RIGDEN.

REFERENCES CITED The following references are of record in the tile 01this Intent:

Number 10 Number 6 UNITED STATES I'A'IINTB Name Date Bewell Aug. 28,1873 Show Feb. 8. 1877 Hawkins Jan. 25, 1927 Holler e Dec. 5, 1933FOREIGN PATENT Country Date Germany Oct. 1, 1889 Great Britain Apr. 10,1922

